The control of a subsea fluid extraction well is normally effected by a subsea electronic control module (SEM) housed within, or located close to, a subsea control module (SCM) mounted on a well tree, situated on the sea bed at the well head. The SEM is provided with electric power and communications via an umbilical line to a control platform, which may be on a vessel or located on land. Typically, the SEM receives commands via the umbilical communication line to its internal electronics. These are then processed by the SEM, and the resulting electrical outputs are sent to electrically-operated production fluid control valves and/or directional control valves (DCVs) housed in the SCM, which control hydraulic power to hydraulically-operated valves. The SEM also feeds data relating to such operations back to the control platform. Additionally, the SEM electronics handles many other functions, which include the collection and interpretation of data from sensors distributed throughout the production system, such as pressure, temperature, fluid flow, microseismic, oil/water quality and, on more recent systems, compressed video and transmits them back to the control platform. The SEM also houses the electronics required to operate a High Integrity Pipeline Protection System (HIPPS) and the electronics for the communication system, such as modems and routers, or in more modern systems, Ethernet interfaces, as well as communication redundancy.
FIG. 1 shows a block diagram of a typical existing SEM. A modem 1 effects external communication, e.g. to the control platform, through an interface A. The modem 1 communicates internally to an SEM processing means 2, which implements commands from the control platform in the form of outputs to driver circuits 3. These in turn output a multiplicity of drives to external devices such as DCVs through interfaces B. External inputs from a multiplicity of interfaces C connect to signal conditioning electronic circuits 4. These external inputs include for example signals from the SCM such as monitoring functions, e.g. pressure and temperature measurements, positions of valves etc which can have a variety of electrical interfaces. The circuits 4 convert these electrical inputs into a suitable interface for processing means 2. The processing means 2 then processes the inputs and either effects control of the well via the interfaces B and/or outputs data via the modem 1 back to the control platform through the interface A. For the processing means 2 to operate, it is necessary to load data and software to it. This is carried out during factory testing and installation, and is achieved relatively slowly via the modem 1 through the interface A.
Typically, modern SEMs employ processors/microcontrollers to implement the functions described above which has resulted in very large software packages and data having to be loaded in. It takes typically seven hours to load the software/data on a current SEM, via its communication modem, due to the relatively slow speed of the modem. This has a major effect on both testing times and cost. Furthermore, the costs involved in having to take this length of time on the installation vessel at the point of installation are highly significant. One possible solution to this problem could be to add a high-speed data link to the SEM, but this would mean that an additional connector has to be added to the SCM electronic interface plate. However, with the prevailing trend to provide smaller and lighter well control systems containing SCMs, the surface area of the SCM connector end plate has become minimal and there is typically not enough room to add another connector. Furthermore, such a connector may be an expensive device.